Lubricants containing olefin copolymer and acrylate copolymer

ABSTRACT

A lubricating oil composition comprising an oil of lubricating viscosity and a total of from about 1 to about 50% by weight of copolymers comprising (A) at least one ethylene-aliphatic olefin copolymer wherein the aliphatic olefins contain from 3 to about 24 carbon atoms, said copolymer (A) having {overscore (M)} n  ranging from about 600 to about 5000, and (B) at least one copolymer comprising units derived from alkyl acrylate ester monomers containing from 2 to about 25 carbon atoms in the ester group, and optionally, from about 0.1% to about 20% by weight of at least one member of the group consisting of vinyl aromatic monomers and nitrogen-containing vinyl monomers. said copolymer (B) having {overscore (M)} n  ranging from about 10,000 to about 350,000, wherein the weight ratio of (A):(B) ranges from about 99:1 to about 1:99.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional patentapplication Serial No. 60/282,988 filed Apr. 11, 2001, the disclosure ofwhich is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] This invention is directed to lubricating oil compositionscomprising polyolefins and polyacrylates. These lubricating oilcompositions display good low temperature and shear performance indriveline lubricants and provide improved efficiency without sacrificingdurability under severe loading conditions. The invention is alsodirected to polymeric compositions comprising mixtures of thepolyolefins and polyacrylates.

BACKGROUND OF THE INVENTION

[0003] When a fluid is subjected to external forces, it resists flow dueto internal friction. Viscosity is a measure of this internal friction.

[0004] The viscosity of oils of lubricating viscosity is generallydependent upon temperature. As the temperature of the oil is increased,the viscosity usually decreases, and as the temperature is reduced, theviscosity usually increases.

[0005] The function of a viscosity improver is to reduce the extent ofthe decrease in viscosity as the temperature is raised or to reduce theextent of the increase in viscosity as the temperature is lowered, orboth. Thus, a viscosity improver ameliorates the change of viscosity ofan oil containing it with changes in temperature. The fluiditycharacteristics of the oil are improved.

[0006] Viscosity improvers are usually polymeric materials and are oftenreferred to as viscosity index improvers.

[0007] It is desirable that viscosity improvers not adversely affect thelow-temperature viscosity of the lubricant containing same. Frequently,while viscosity improvers enhance the high temperature viscositycharacteristics of lubricating oil, that is, they reduce the loss ofviscosity with increasing temperature, low temperature properties of thetreated lubricant become worse. It is also desirable that viscosityimproving agents provide relatively constant fluidity characteristicsunder extended periods of use. Such materials usually are polymers thatresist shearing.

[0008] While many lubricating oil compositions can benefit from the useof viscosity improvers, gear lubricants and automatic transmissionfluids are particularly sensitive to viscosity.

[0009] Gear lubricants are subjected to high levels of shearing underuse. While many conventional viscosity improving agents providelubricants with exemplary viscosity characteristics when first prepared,after a short period of use lubricating a gear set, such as in anautomobile or truck axle or transmission, the viscosity improving agentundergoes shearing, resulting in reduced viscosity improving properties.The loss of viscosity with shearing is a permanent loss. That is, thelost viscosity cannot be recovered by ordinary physical means. Theeffectiveness at high and low temperature is reduced.

[0010] Gear lubricants also preferably have good low temperatureviscosity characteristics.

[0011] In automatic transmission fluids (ATF) and other drivelinelubricants and crankcase lubricants, viscosity modifiers are often usedto improve relative low and high temperature characteristics. In ATF therequirements are currently for viscosity at −40° C. to be in the rangeof 7,000 to 20,000 centipoise (cP) and kinematic viscosity at 100° C.ranging from about 6.5 to about 8.5 centistokes (cSt). More recently,especially for factory fill requirements, shear stability has beenincluded as a performance requirement. A further goal is to reducetreatment levels of viscosity modifiers, providing both a cost benefitand a performance benefit.

[0012] Other lubricating oil compositions that can benefit from thisinvention include hydraulic fluids, for example farm tractor fluids,industrial hydraulic application fluids and the like, lubricants forcontinuously variable transmissions (CVT), for example push-belt andchain drive CVT, dual clutch transmissions, manual transmissions, andothers where viscosity characteristics of the lubricant are particularlyimportant.

[0013] The United States Environmental Protection Agency has institutedstringent automobile-related environmental regulations. A primary focusof the regulations relates to Corporate Average Fuel Economy (CAFE)standards, which mandate a specified, gradual increase of a corporatefleet's overall fuel economy by established target dates. The effort toincrease fuel economy has become paramount in the wake of theEnvironmental Protection Agency's (EPA) tightening CAFE standards.

[0014] CAFE standards have spurred industry wide research anddevelopment of engines and lubricants therefor. More recently, theeffect of driveline components on fuel economy has become of increasedinterest.

[0015] In particular, the effect of axle efficiency on fuel economy hasbeen given increased attention. Multigraded gear oils, such as SAE75W-140 grade axle oils provide outstanding durability, resulting inoperating temperature reduction and extended axle life under conditionsof severe duty. These lubricants are generally recommended for use inaxles of the highly popular light trucks and sport utility vehicles(SUV) presently on the market. However, the higher viscositieshistorically required for axle lubricants for more heavily loaded SUVand light truck applications are not consistent with currently mandatedCAFE targets for improved fuel economy.

[0016] Lighter viscosity grades are more appropriate for energyefficiency because of reduced frictional ‘drag’ and greateraccessibility to critical moving parts. For example, a commerciallyavailable SAE 75W-90 synthetic gear oil provides good fuel economy butlacks durability for severe service such as trailer towing.

[0017] It is well known to those skilled in the art that componentswhich may provide a benefit in one aspect may seriously degradeperformance of another aspect. Frequently, this arises from an adverseinteraction between different components in a lubricating oilcomposition. The challenge here is to build both durability and energyefficiency into a single lubricating composition without compromisingcritical areas such as scoring protection, bearing fatigue, sealintegrity and corrosion resistance.

[0018] Traditionally, for the formulator of ATF, continuously variabletransmissions (CVT), traction drive and other driveline lubricants,research and formulating has centered around the design and or selectionof a viscosity modifier with the best combination of attributes. Somepatents exist relating to combinations of viscosity improvers which aresaid to provide special benefits.

[0019] In U.S. Pat. No. 4,594,378, and U.S. Pat. Nos. 4,654,403 and4,734,446 which are divisionals of U.S. Pat. No. 4,594,378, polymericcompositions useful as additives in transmission fluids and hydraulicfluids are described which comprise a mixture of (A) at least oneoil-soluble polymer which is a homopolymer of a non-aromatic monoolefinor a copolymer of said non-aromatic monoolefin with an aromaticmonoolefin, and (B-1) at least one nitrogen-containing ester of acarboxy-containing interpolymer, and/or (B-2) at least one oil-solubleacrylate polymerization product of at least one acrylate ester, or amixture of one or more of (B-1) and (B-2), and the transmission fluidsand hydraulic fluids containing the polymeric compositions are said toexhibit improved shear stability while maintaining desirable high andlow temperature viscosity characteristics. The polymeric compositionsalso may contain (C) an effective amount of at least one low temperatureviscosity-reducing liquid organic diluent such as a naphthenic oil orcertain other natural and synthetic oils having the desired lowtemperature properties.

[0020] U.S. Pat. No. 5,108,635 relates to a composition of matter,particularly useful as a viscosity additive, based on an olefincopolymer and a polyalkyl methacrylate in diluent oil solution, whichcomposition comprises from 6 to 15 parts by weight of at least oneethylene-propylene copolymer having a weight-average molecular massranging from approximately 155,000 to approximately 250,000, andexhibiting an ethylene/propylene weight ratio ranging from 60/40 to54/46, from 2 to 8 parts by weight of at least one poly(C₁₋₂₀ alkylmethacrylate), ungrafted or grafted with 1 to 8% of its weight of adispersant monomer, the polymethacrylate having a weight-averagemolecular mass ranging from 30,000 to 150,000, the ungrafted or graftedpolymethacrylate/ethylene-propylene copolymer weight ratio ranging from1/5 to 1/1, and the complement to 100 parts by weight of diluent oil.

[0021] U.S. Pat. No. 5,883,057 relates to a lubricating compositioncomprising at least about 30% by weight of at least one mineral oil,having a kinematic viscosity of less than about 8 cSt at 100° C., (A)from about 5% to about 30% by weight at least one polymer having an{overscore (M)}_(w) less than about 10,000, and (B) from about 2% toabout 12% by weight of a polymer having a {overscore (M)}_(w) greaterthan about 15,000, wherein the lubricating composition has a shear lossof less than about 15% in the 20 hour taper bearing shear test. In oneaspect, the lubricating compositions may also include (C) from about 5%to about 30% by weight of at least one fluidizing agent. The patent alsorelates to concentrates used in preparing shear stable lubricatingcompositions. The combination of components is said to provide good lowand high temperature properties to mineral oils, even at high treatlevels. The lubricants have good shear stability and in one aspect haveimproved oxidation resistance.

[0022] U.S. Pat. No. 5,821,313 is directed to a process for preparing anitrogen containing copolymer, the copolymers and lubricating oilcompositions containing the copolymers. The process comprises reacting,in the presence of a free radical initiator, (A) from about 55% to about99.9% by weight of one or more alkyl acrylate ester monomers containingfrom 1 to about 24 carbon atoms in the ester alkyl group, wherein atleast about 50 mole % of the esters contain at least 6 carbon atoms inthe ester alkyl group, and (B) from about 0.1% to about 45% by weight ofat least one nitrogen containing monomer selected from the groupconsisting of vinyl substituted nitrogen heterocyclic monomers,dialkylaminoalkyl acrylate monomers, dialkylaminoalkyl acrylamidemonomers, N-tertiary alkyl acrylamides, and vinyl substituted aminesprovided that the total of (A) and (B) equals 100%, and optionally, inthe presence of a chain transfer agent, wherein monomer (A), the freeradical initiator, and if used, the chain transfer agent, are firstcombined to form a mixture, whereupon from about 10% to about 80% ofsaid mixture is mixed with monomer (B); from about 20% to about 100% ofthe mixture of monomers (A) and (B) is heated until an exotherm isnoted, then while maintaining reaction temperature, first adding thebalance, if any, of the mixture of monomers (A) and (B), over about 0.25hour to about 5 hours followed by addition over 0.25 to about 5 hours ofthe remaining mixture of monomer (A) and initiator, optionally addingadditional initiator, whereupon the reaction is continued to completion.

[0023] U.S. Pat. No. 6,124,249 describes a copolymer comprising unitsderived from (a) methacrylic acid esters containing from about 9 toabout 25 carbon atoms in the ester group and (b) methacrylic acid esterscontaining from 7 to about 12 carbon atoms in the ester group, saidester groups having 2-(C₁₋₄ alkyl)-substituents, and optionally (c) atleast one monomer selected from the group consisting of methacrylic acidesters containing from 2 to about 8 carbon atoms in the ester group andwhich are different from methacrylic acid esters (a) and (b), vinylaromatic compounds, and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group.

[0024] PCT Publication WO 00/71646 describes mineral oil based gear oilsand transmission fluids which comprise a major amount of a mineral oilhaving an iodine number of less than 9 and where at least 55% of thesaturates are aliphatic, and gear oil or transmission fluid additives.In one embodiment, the invention relates to a gear oil or transmissionfluid composition comprising a major amount of lubricant basestock andat least one functional additive wherein a major amount of the lubricantbasestock comprises a mineral oil having an iodine number of less than 9and comprising at least 45% by weight of aliphatic saturates. These gearoils and transmission fluids have good viscosity and oxidationproperties.

SUMMARY OF THE INVENTION

[0025] The present invention relates to lubricating oil compositionscomprising an oil of lubricating viscosity and a total of from about 1to about 50% by weight of copolymers comprising (A) at least oneethylene-aliphatic olefin copolymer wherein the aliphatic olefinscontain from 3 to about 24 carbon atoms, said copolymer (A) having{overscore (M)}_(n) ranging from about 600 to about 5000, and (B) atleast one copolymer comprising units derived from alkyl acrylate estermonomers containing from 2 to about 25 carbon atoms in the ester group,and optionally, from about 0.1% to about 20% by weight of at least onemember of the group consisting of vinyl aromatic monomers andnitrogen-containing vinyl monomers, said copolymer (B) having {overscore(M)}_(n) ranging from about 10,000 to about 350,000, wherein the weightratio of (A):(B) ranges from about 99:1 to about 1:99.

[0026] In another embodiment, this invention is directed to a polymericcomposition comprising a mixture of from about 1% to about 99% by weightof (A) at least one ethylene-aliphatic olefin copolymer wherein thealiphatic olefins contain from 3 to about 24 carbon atoms, saidcopolymer (A) having number average molecular weight ranging from about600 to about 5000, and from about 99% to about 1% by weight of (B) atleast one copolymer comprising units derived from alkyl acrylate estermonomers containing from 2 to about 25 carbon atoms in the ester group,and optionally, from about 0.1% to about 20% by weight of units derivedfrom at least one member of the group consisting of vinyl aromaticmonomers and nitrogen-containing vinyl monomers. said copolymer (B)having number average molecular weight ranging from about 10,000 toabout 350,000.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The above combination of polymers are useful in lubricants wherethey can be used in automatic or manual transmission fluids, transaxlelubricants, gear lubricants, both for open and enclosed systems, tractorlubricants, metal-working lubricants, hydraulic fluids and otherlubricating oil and grease compositions.

[0028] The lubricants of the present invention include automatictransmission, manual transmission and gear lubricants. The transmissionlubricants include those that meet the General Motors DEXRON® III andFord MERCON® and MERCON® V automatic transmission fluid requirements. Inone embodiment, the lubricants include heavy duty or off roadtransmissions such as those meeting the Allison C-4 specification. Inanother embodiment, the lubricants are gear lubricants and include GL4and GL5 lubricants. Additionally, in another embodiment, the lubricantsare MT-1 lubricants.

[0029] As described herein, the present invention relates to lubricatingoil compositions, and particularly gear oil and transmission fluidcompositions. which comprise an oil of lubricating viscosity. The oil oflubricating viscosity may be a singular component or may be acombination of components to be combined with functional additives. Inone embodiment, the basestock comprises a major amount of the mineraloils discussed below. The minority of the basestock may be composed ofother mineral oils or polyalphaolefins. The lubricating oil compositionsof this invention, may additionally contain at least one functionaladditive. The functional additive adds an additional characteristic tothe compositions in addition to those properties provided by the oil oflubricating viscosity. Examples of such functions include antiwear,extreme pressure, antioxidancy, friction modification, etc.

[0030] Lubricating compositions are often subjected to high shearconditions. Lubricating oils containing a polymer can experienceshearing of the polymer, resulting in reduction of viscosity improvingproperties. Accordingly, shear stability of polymer containinglubricating oils is frequently important.

[0031] As described herein, a particularly effective combination ofviscosity modifying polymers has been discovered that providesunexpectedly good performance on low temperature viscosity and shearstability in a wide variety of lubricating applications as well asexcellent performance under conditions of severe duty such as in axlesof light trucks and SUV. while still providing satisfactory fuelefficiency. At the same time, compared to treatment with a singleviscosity improver, the combination also allows a substantial, often asmuch as 30-50%, reduction in viscosity modifier treatment levelsresulting in improved formulation economics.

[0032] As noted hereinabove and discussed in greater detail hereinafter,the compositions of this invention comprise particularethylene-aliphatic olefin copolymers and particular copolymers of alkylacrylate ester monomers.

[0033] As noted herein, lubricating oil compositions displaying goodviscosity control and shear stability are desired.

[0034] Another property of interest is traction. Traction is essentiallya measure of the internal resistance of a fluid to flow. It is aphysical property related to the bulk fluid and is manifested under fullfluid film lubrication. As defined herein, traction is a function of thefluid's molecular structure. Performance additives which activate underboundary or mixed-film conditions where various degrees ofmetal-to-metal contact occur don't significantly contribute to thetractive effect.

[0035] Traction properties of fluids and thickeners are among indicatorsof operating temperatures that might be encountered in gear andtransmission oils where constant churning generates frictional heat.Traction properties play a role in the losses incurred directly by thefluid, especially in lightly loaded situations. In a heavily loadedsituation, a low traction coefficient fluid would be expected to run ata lower temperature than one with a higher traction coefficient.

[0036] For a given fluid at a constant temperature, a profile oftraction coefficient versus slide-to-roll ratio can be determinedemploying a commercially available test rig known as the Mini-TractionMachine (MTM) available from PCS Instruments, London, U.K., an apparatuswherein a highly polished steel ball bearing is loaded against a highlypolished steel disc. Both the ball and disc are rotated in relativemotion against each other while the velocity of each element isindependently controlled. A desired amount of slip is introduced at theinterface under different rolling velocities. Traction behavior offluids can be compared by superimposing their traction profiles;alternatively, traction coefficients can be compared at given slide-rollratios.

[0037] Synthetic basestocks, particularly poly-alphaolefin oils andAmerican Petroleum Institute (API) Group III oils, described in greaterdetail elsewhere herein, are known to have lower traction coefficientscompared to API Group I and Group II mineral oils. For gear oilapplications, it is particularly preferred to employ low tractioncoefficient fluids as the oil of lubricating viscosity.

[0038] As noted hereinabove, axle durability equates to reducedoperating temperatures under high torque conditions such as trailertowing.

[0039] One way to measure axle durability is to employ a test rigdesigned to apply multiple stages of loading and speed, such as (1) highload-low speed simulating trailer tow start up; (2) moderate loading athigh speed; (3) moderate load-moderate to high speed simulating cruiseconditions, (4) moderate to high load at somewhat reduced speed alsosimulating cruise conditions, and (5) further increased load withfurther reduction in speed simulating uphill travel, wherein theseconditions simulate a variety of trailer towing conditions. Key piecesof information obtained from the evaluation are stabilized operatingtemperature of the lubricant and average efficiency under various teststages.

[0040] Actual fuel economy performance is conducted employing the EPA55/45 cycle set out in Title 40, Code of Federal Regulations, based onthe assumption of typical use pattern of 55% city driving and 45%highway driving.

[0041] As used herein, the terms “hydrocarbyl” and “hydrocarbon based”mean that the group being described has predominantly hydrocarboncharacter within the context of this invention. These include groupsthat are purely hydrocarbon in nature, that is, they contain only carbonand hydrogen. They may also include groups containing substituents oratoms which do not alter the predominantly hydrocarbon character of thegroup. Such substituents may include halo-, alkoxy-, nitro-, etc. Thesegroups also may contain hetero atoms. Suitable hetero atoms will beapparent to those skilled in the art and include, for example, sulfur,nitrogen and oxygen. Therefore, while remaining predominantlyhydrocarbon in character within the context of this invention, thesegroups may contain atoms other than carbon present in a chain or ringotherwise composed of carbon atoms provided that they do not adverselyaffect reactivity or utility of the process or products of thisinvention.

[0042] In general, no more than about three non-hydrocarbon substituentsor hetero atoms, and preferably no more than one, will be present forevery 10 carbon atoms in the hydrocarbon or hydrocarbon based groups.Most preferably, the groups are purely hydrocarbon in nature, that is,they are essentially free of atoms other than carbon and hydrogen.

[0043] Throughout the specification and claims the expression oilsoluble or dispersible is used. By oil soluble or dispersible is meantthat an amount needed to provide the desired level of activity orperformance can be incorporated by being dissolved, dispersed orsuspended in an oil of lubricating viscosity. Usually, this means thatat least about 0.001% by weight of the material can be incorporated intoa lubricating oil. For a further discussion of the terms oil soluble anddispersible, particularly “stably dispersible”, see U.S. Pat. No.4,320,019 which is expressly incorporated herein by reference forrelevant teachings in this regard.

[0044] The expression “lower” is used throughout the specification andclaims. As used herein to describe various groups, the expression“lower” is intended to mean groups containing no more than 7 carbonatoms, more often, no more than 4, frequently one or two carbon atoms.

[0045] It must be noted that as used in this specification and appendedclaims, the singular forms also include the plural unless the contextclearly dictates otherwise. Thus the singular forms “a”, “an”, and “the”include the plural; for example “a monomer” includes mixtures ofmonomers of the same type. As another example, the singular form“monomer” is intended to include both singular and plural unless thecontext clearly indicates otherwise.

[0046] In the context of this invention the term “copolymer” means apolymer derived from two or more different monomers. Thus, a polymerderived from a mixture of, for example, 2 or more of methyl-, butyl-,heptyl-, nonyl-, decyl-, etc. methacrylates is a copolymer as definedherein. Likewise a polymer derived from one of C₉₋₁₁-, andC₁₂₋₁₈-methacrylates, or a polymer having two or more distinct blocks,is a copolymer as defined herein. The copolymers of this invention alsomay contain units derived from nitrogen-containing monomers.

[0047] The expression viscosity index (often abbreviated VI), isfrequently used herein. Viscosity index is an empirical numberindicating the degree of change in viscosity within a given temperaturerange. A high VI signifies an oil that displays a relatively smallchange in viscosity with temperature.

[0048] The copolymers of this invention may be prepared in the presenceof a diluent. A diluent may also be added to a substantiallydiluent-free copolymer, usually by dissolving or dispersing thesubstantially diluent-free polymer in an appropriate diluent. In anotherembodiment, an additional diluent, often a higher boiling diluent suchas an oil, may be added to a copolymer which was prepared in, and stillcontains, a lower boiling diluent which is then removed by commonmethods such as distillation. Preferably, when the polymer is preparedin the presence of a diluent, the diluent is an oil.

[0049] In one embodiment, the diluent is a mineral oil. In a particularembodiment the mineral oil consists essentially of hydrotreatednaphthenic oil. Also contemplated are hydrodewaxed mineral oils. Thediluent may also be a synthetic oil. Common synthetic oils are estertype oils, polyolefin oligomers or alkylated benzenes.

[0050] The expression “substantially inert” is often used in referenceto diluents. When used in this context, “substantially inert” means thediluent is essentially inert with respect to any reactants orcompositions of this invention, that is, it will not, under ordinarycircumstances, undergo any significant reaction with any reactant orcomposition, nor will it interfere with any reaction or composition ofthis invention.

[0051] (A) Copolymer of Aliphatic Olefins

[0052] Copolymer (A) comprises at least one ethylene-aliphatic olefincopolymer wherein the aliphatic olefins, preferably alpha olefins,contain from 3 to about 24 carbon atoms, said copolymer having{overscore (M)}_(n) ranging from about 600 to about 5000, preferablyfrom about 800 to about 4000 and more preferably from about 2000 toabout 4000 and polydispersity values ({overscore (M)}_(w)/{overscore(M)}_(n)) ranging from about 1.1 to about 3, more often from about 1.3to about 2.5, and frequently from about 2.0 to about 2.4.

[0053] In one embodiment, the copolymer comprises an ethylene-alphaolefin copolymer. In one typical embodiment, the ethylene content of thecopolymer ranges from about 30 mole % to about 85 mole %, often fromabout 45 to about 55 mole %. Preferably, the copolymer is anethylene-propylene copolymer.

[0054] In one preferred embodiment, the copolymer is anethylene-propylene copolymer wherein the ethylene content ranges fromabout 40 mole % to about 85 mole %, more often from about 45 to about 55mole %. These are commercially available, for example as LUCANT(TM)Hydrocarbon-Based Synthetic Oil marketed by Mitsui Petrochemicals(America) Ltd., New York, N.Y., USA.

[0055] Copolymer (A) can be formed by copolymerization of ethylene andone or more aliphatic olefins under conditions known in the art.Examples include polymerizations conducted using Ziegler-Natta ormetallocene catalysts.

[0056] (B) Acrylate Ester Copolymers

[0057] Copolymer (B) comprises an acrylate copolymer. Included withinthe definition of ‘acrylate copolymers’ are esters of acrylic acids, andthe corresponding alkacrylic-, especially methacrylic-, compounds,particularly alkyl methacrylates. at least one copolymer comprisingunits derived from alkyl acrylate ester monomers containing from 2 toabout 25 carbon atoms in the ester group, and optionally, from about0.1% to about 20% by weight of at least one member of the groupconsisting of vinyl aromatic monomers and nitrogen-containing vinylmonomers. said copolymer (B) having {overscore (M)}_(n) ranging fromabout 10,000 to about 350,000, wherein the weight ratio of (A):(B)ranges from about 99:1 to about 1:99 and preferably from about 25:75 toabout 75:25.

[0058] In reference to the size of the ester groups, it is pointed outthat an ester group is represented by the formula

—C(O)(OR)

[0059] and that the number of carbon atoms in an ester group is thecombined total of the carbon atom of the carbonyl group and the carbonatoms of the (OR) group. Thus, methyl methacrylate contains two carbonatoms in the ester group. A butyl ester contains five carbon atoms inthe ester group.

[0060] In one embodiment, copolymer (B) comprises units derived frommonomers comprising from about 5% to about 75% by weight of alkylacrylate ester monomers containing from 2 to 12 carbon atoms in theester group and from about 25% to about 95% by weight of alkyl acrylateester monomers containing from 13 to about 25 carbon atoms in the estergroup.

[0061] In another embodiment, copolymer (B) comprises units derived from

[0062] (a) about 35 mole % to about 95 mole % of alkyl methacrylateester monomers containing from about 9 to about 25 carbon atoms in theester group and

[0063] (b) about 65 mole % to about 5 mole % of alkyl methacrylate estermonomers containing from about 7 to about 12 carbon atoms in the estergroup, and optionally

[0064] (c) from about 0.1 mole % to about 20 mole % of units derivedfrom at least one member of the group consisting of alkyl methacrylateester monomers containing from 2 to about 8 carbon atoms in the estergroup, which esters are different from methacrylate esters (a) and (b),vinyl aromatic monomers and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group.

[0065] In a particular embodiment, copolymer (B) comprises units derivedfrom

[0066] (a) about 35 mole % to about 95 mole % of alkyl methacrylateester monomers containing from about 13 to about 25 carbon atoms in theester group and

[0067] (b) about 65 mole % to about 5 mole % of alkyl methacrylate estermonomers containing from about 7 to about 12 carbon atoms in the estergroup.

[0068] In another embodiment, copolymer (B) further comprises from about0.1 mole % to about 20 mole % of units derived from (c) at least onemember of the group consisting of alkyl methacrylate ester monomerscontaining from 2 to about 8 carbon atoms in the ester group, whichesters are different from methacrylate esters (a) and (b), vinylaromatic monomers and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group.

[0069] In one embodiment, copolymer (B) may contain from about 0.1% toabout 10% by weight of units derived at least one nitrogen containingvinyl monomer. In this case, copolymer (B) typically displays not onlyviscosity improving properties but also dispersant properties. Preferrednitrogen containing vinyl monomers are selected from the groupconsisting of vinyl substituted nitrogen heterocyclic monomers,dialkylaminoalkyl acrylate monomers, dialkylaminoalkyl acrylamidemonomers, N-tertiary alkyl acrylamides, and vinyl substituted amines.

[0070] In one particularly preferred embodiment, the alkyl moieties ofthe ester groups of alkyl methacrylate ester monomer (b) have 2-(C₁₋₄alkyl) substituents. Particularly preferred is where monomer (b)comprises 2-ethylhexyl methacrylate.

[0071] Acrylate copolymers like these are known and are described innumerous U.S. patents including U.S. Pat. Nos. 5,108,635; 5,534,175;5,696,068; 5,821,313; and 6,124,249, each of which is incorporatedherein by reference for relevant disclosures contained therein.

[0072] Acrylate copolymers useful in the present invention are preparedby methods known in the art, several of which are disclosed in theforegoing patents.

[0073] In one embodiment, copolymer (B) can be prepared by a processcomprising reacting, in the presence of a free radical initiator, one ormore alkyl acrylate ester monomers containing from 2 to about 25 carbonatoms in the ester group, and optionally, from about 0.1% to about 20%by weight of at least one member of the group consisting of vinylaromatic monomers and nitrogen-containing vinyl monomers.

[0074] In another embodiment, copolymer (B) can be prepared by a processcomprising reacting, in the presence of a free radical initiator, one ormore alkyl acrylate ester monomers containing from 2 to about 25 carbonatoms in the ester group, and from about 0.1% to about 20% by weight ofat least one member of the group consisting of vinyl aromatic monomersand nitrogen-containing vinyl monomers, optionally, in the presence of achain transfer agent, wherein the acrylate monomers, the free radicalinitiator, and if used, the chain transfer agent, are first combined toform a mixture, whereupon from about 10% to about 80% of said mixture ismixed with the second monomer; then from about 20% to about 100% of themixture of monomers is heated until an exotherm is noted, then whilemaintaining reaction temperature, first adding the balance, if any, ofthe mixture of monomers over about 0.25 hour to about 5 hours followedby addition over 0.25 to about 5 hours of the remaining mixture ofacrylate ester monomers and initiator, optionally adding additionalinitiator, whereupon the reaction is continued to completion.

[0075] In one preferred embodiment, the alkyl acrylate monomerscomprises at least about 50 mole % of the esters containing at least 6carbon atoms in the ester group.

[0076] In one preferred embodiment, (B) is a copolymer prepared by aprocess comprising reacting, in the presence of a free radical initiator

[0077] (1) from about 55% to about 99.9% by weight of one or more alkylacrylate ester monomers containing from 2 to about 25 carbon atoms inthe ester group, wherein at least about 50 mole % of the esters containat least 6 carbon atoms in the ester group, and

[0078] (2) from about 0.1% to about 45% by weight of at least onemonomer selected from the group consisting of acrylic acid esterscontaining from 2 to about 8 carbon atoms in the ester group and whichare different from acrylic acid esters (a), vinyl aromatic monomers andnitrogen-containing vinyl monomers, with the proviso that no more than60% by weight of the esters contain not more than 11 carbon atoms in theester group, and optionally, in the presence of a chain transfer agent,wherein monomer (1), the free radical initiator, and if used, the chaintransfer agent, are first combined to form a mixture, whereupon fromabout 10% to about 80% of said mixture is mixed with monomer (2) to forma second mixture; from about 20% to about 100% of the mixture ofmonomers (1) and (2) is heated until an exotherm is noted, then whilemaintaining reaction temperature, first adding the balance, if any, ofthe mixture of monomers (1) and (2) over about 0.25 hour to about 5hours followed by addition over 0.25 to about 5 hours of the remainingmixture of monomer (1) and initiator, optionally adding additionalinitiator, whereupon the reaction is continued to completion.

[0079] Chain Transfer Agents

[0080] The process to prepare the acrylate copolymers may be conductedin the presence of a chain transfer agent. The use of chain transferagents to regulate and limit molecular weight in polymer reactions isknown, see for example “Concise Encyclopedia of Polymer Science andEngineering”, J. I. Kroschwitz, Ed., Wiley-Interscience (New York,1990), page 139. An extensive discussion of chain transfer, its effects,and chain-transfer agents together with an extensive bibliography,appears in the “Encyclopedia of Polymer Science and Technology”, H. F.Mark, N. G. Gaylord, and N. M. Bikales, Eds., Interscience, (New York,1965), pp. 575-610. Both of these are expressly incorporated herein byreference.

[0081] Sulfur compounds, especially mercaptans, particularly dodecylmercaptans, for example, n- and tertiary dodecyl mercaptans, arepreferred.

[0082] Polymerization can take place under a variety of conditions,among which are bulk polymerization, solution polymerization, emulsionpolymerization, suspension polymerization and nonaqueous dispersiontechniques.

[0083] Copolymer (B) is prepared employing conventional methods ofradical polymerization.

[0084] Such methods are described in the work “Encyclopedia of PolymerScience and Engineering” (H. F. Mark, N. M. Bikales, C. G. Overbergerand G. Menges), 2nd edition (1988), published by Wiley Interscience.

[0085] These methods include free-radical initiated polymerizationemploying azo compounds or peroxides. Also described therein arephotochemical and radiation initiated methods.

[0086] Initiators

[0087] Free radical generating reagents useful as polymerizationinitiators are well known to those skilled in the art. Numerous examplesof free radical initiators are mentioned in texts by Flory and Bovey andWinslow mentioned hereinafter. An extensive listing of free radicalinitiators appears in J. Brandrup and E. H. Immergut, Editors, “PolymerHandbook”, 2nd edition, John Wiley and Sons, New York (1975), pp. II-1to II-40. Numerous free radical initiators are available and many arecommercially available in large quantities. Useful initiators includeorganic peroxides, hydroperoxides and azo compounds. Redox initiatorsare also useful.

[0088] Examples of free radical initiators are t-butyl peroxide, t-butylhydroperoxide, t-amyl peroxide, cumyl peroxide, dibenzoyl peroxide(Aldrich), t-butyl m-chloroperbenzoate, azobisvaleronitrile, t-butylperoctoate and tertiary-butyl perbenzoate, (TRIGONOX® 21 and TRIGONOX®C, respectively, both from AKZO) and 2,2′-azobis(isobutyronitrile),VAZO®-64, and, 2,2′-azobis(methylbutyronitrile), VAZO®-67, both fromDuPont.

[0089] Free radical initiators are usually used in amounts ranging fromabout 0.01% to about 10 percent by weight based on the total weight ofreaction mixture. Generally, the initiators are used at about 0.05% toabout 3% by weight, even more often from about 0.1 to about 2%,frequently from about 0.5% to about 1.5% or to about 1% by weight.

[0090] The choice of free radical initiator can be an importantconsideration. Considerations include the half-life of the initiator ata given temperature, nature of the reactants, reaction temperature,solvent or diluent, and the like.

[0091] Molecular weights of the polymer (B) can be controlled employinga number of techniques including choice of initiator, reactiontemperature, concentration of monomers and solvent type. As notedpreviously, chain transfer agents can be used.

[0092] Copolymer (B) used in the present invention are generallyprepared at reaction temperatures ranging from about 40° C. to about200° C., frequently, from about 60° C. to about 160° C.

[0093] Because acrylic polymerizations may be accompanied by liberationof considerable heat, care must be taken to avoid uncontrolled reaction.Temperatures can be controlled by using reactors with cooling jackets,controlling rates of addition and use of reaction solvents.

[0094] The following examples are intended to illustrate severalcopolymers (B) of this invention as well as means for preparing same.Unless indicated otherwise all parts are parts by weight. It is to beunderstood that these examples are intended to illustrate severalcompositions and procedures and are not intended to limit the scope ofthe invention. Molecular weight values are determined employing gelpermeation chromatography (GPC) employing well-characterizedpolymethacrylate (PMA) calibration standards. PDI is the polydispersityindex, Mw/Mn. Filtrations are conducted using a diatomaceous earthfilter aid.

EXAMPLE 1

[0095] A vessel is charged with 520 parts of a C₁₂₋₁₅ methacrylate(which contains less than 1% by weight of C₁₆-C₁₈ methacrylate), 280parts 2-ethylhexyl methacrylate, 94.5 parts mineral oil (Total 85N),10.5 parts t-butylperoxy-2-ethylhexanoate (Trigonox T21S), 10.5 partsn-dodecanethiol, and 61.4 parts a hydrotreated naphthenic oil (RisellaG07, Shell Germany) and stirred for 0.2 hour. One third of the mixture(326 parts) is charged to a reactor. An N₂ blanket is maintainedthroughout the reaction. The materials in the reactor are heated to 100°C. over 0.2 hour whereupon an exotherm to 139.6° C. over 4 minutes isobserved and heating is discontinued. After the peak exotherm isattained, the remaining 2/3 of the monomer/initiator/oil mixture isadded over 1.5 hour. The temperature drops to 110° C. during addition.The temperature is then maintained at 110° C.+/−3° C. for 2 hours. Anadditional 0.7 part Trigonox T21S in 6.3 parts 85N oil is added followedmixing for an additional 2.0 hours at 110° C.+/−3° C. The materials aremixed with an additional 39.45 parts Total 85N oil, stirred for 1 hourthen heated to 120° C. and filtered. Viscosity (ASTM D-445) @ 100°C.=356 centistokes.

EXAMPLE 2

[0096] A vessel is charged with 272.8 parts of a C₁₂₋₁₅ methacrylate(which contains less than 1% by weight of C₁₆-C₁₈ methacrylate), 120parts 2-ethylhexyl methacrylate, 73 parts 75N mineral oil (Pennzoil75HC), 3 parts t-butylperoxy-2-ethylhexanoate (Trigonox T21) dissolvedin 27 parts Pennzoil 75HC and 3 parts n-dodecanethiol and stirred for0.2 hour. One third of the mixture (170 parts) is charged to a reactorfollowed by the addition of 7.2 parts N-(3-(dimethylamino)propylmethacrylamide and stirred under N₂ blanket for 0.1 hour. An N₂ blanketis maintained throughout the reaction. The materials in the reactor areheated to 110° C. over 0.25 hour whereupon an exotherm is observed andheating is discontinued. The exotherm is to 138° C. over 2 minutes.After the peak exotherm is attained, the temperature drops to 137° C.whereupon the remaining 2/3 of the monomer/initiator/oil mixture isadded over 1.5 hour. The temperature drops to 110° C. about 0.2 hourafter addition is started. The temperature is then maintained at 110°C.+/−3° C. for 1.5 hours. An additional 0.5 part Trigonox T21 in 4.5parts Pennzoil 75HC oil is charged followed by heating at 110° C.+/−3°C. for an additional 2.5 hours. The materials are vacuum stripped at135° C. at 50 mm Hg pressure for 0.5 hour. To the residue are added 33.1parts Pennzoil 75HC followed mixing for an additional 0.5 hours andfiltration The product contains 0.22% N and has viscosity (ASTM D-445) @100° C.=502.7 centistokes.

EXAMPLE 3

[0097] A container is charged with 33.9 parts methyl methacrylate, 7.5parts butyl methacrylate, 133.6 parts C₉-C₁₁ methacrylate, 133.6 partsC₁₂-C₁₅ methacrylate, 67.7 parts C₁₆-C₁₈ methacrylate, 13.65 partsN-vinyl pyrrolidinone and 130 parts Risella G 07 oil. The materials arestirred for 0.25 hour, then a solution of 1.56 part VAZO-67 in 3.1 partstoluene is added followed by stirring for 0.1 hour. A reactor equippedas described in Example 1 is charged with about 1/3 of this solution;the remainder is placed in the addition funnel. With stirring and N₂addition at 0.3 SCFH, the mixture is heated to 110° C. over 0.3 hour,heating is stopped and the temperature rises exothermically to 138° C.over 3 minutes. The temperature then begins to drop and after 2 minutesis at 136° C. Dropwise addition of the remaining monomer-initiatormixture is begun and is continued for 2 hours. Temperature decreases to110° C. after 0.3 hours and is held at 110° C. during addition. Afteraddition is completed, the mixture is cooled to 90° C. over 0.3 hourfollowed by charging 0.25 part Trigonox 21. The materials are stirred at90° C. for 2 hours, 0.26 part Trigonox 21 is charged and the materialsare heated for an additional 2 hours. The materials are diluted with 80parts additional Risella G 07 oil, heated with stirring to 150° C., andstripped at 150° C., 40-50 mm Hg pressure for 1 hour, collecting 1 partdistillate. The residue is filtered at 110° C. with a diatomaceous earthfilter aid. The filtrate contains a polymer having M_(n)=68,000 andM_(w)/M_(n)=2.91.

[0098] While the processes to prepare the copolymers used in thecompositions of the instant invention are often conducted inconventional reactors employing agitation means including mechanicalstirrers and/or circulating pumps, another useful means for preparingcopolymers is to employ a high energy mechanical mixing device. Theseinclude roll mills, ball mills or extruders. Of these, extruders arepreferred since the comonomers can be fed to the feed hopper in anydesired fashion. Methods of employing such devices, and especiallyextruders, are described in a number of patents including Hayashi et al,U.S. Pat. No. 4,670,173 and Sopko et al, U.S. Pat. No. 5,039,433, bothof which are expressly incorporated herein by reference.

[0099] The copolymers used in the compositions of this invention may beprepared in the presence of a diluent. A diluent may also be added to asubstantially diluent-free copolymer, usually by dissolving ordispersing the substantially diluent-free polymer in an appropriatediluent. In another embodiment, an additional diluent, often a higherboiling diluent such as an oil, may be added to a copolymer which wasprepared in, and still contains, a lower boiling diluent which is thenremoved by common methods such as distillation. Preferably, when thepolymer is prepared in the presence of a diluent, the diluent is an oil.

[0100] In one embodiment, the diluent is a mineral oil. In a particularembodiment the mineral oil consists essentially of hydrotreatednaphthenic oil. Also contemplated are hydrodewaxed mineral oils. Thediluent may also be a synthetic oil. Common synthetic oils are estertype oils, polyolefin oligomers or alkylated benzenes.

[0101] The expression “substantially inert” is often used in referenceto diluents. When used in this context, “substantially inert” means thediluent is essentially inert with respect to any reactants orcompositions of this invention, that is, it will not, under ordinarycircumstances, undergo any significant reaction with any reactant orcomposition, nor will it interfere with any reaction or composition ofthis invention.

[0102] Molecular weights of polymers are determined using well-knownmethods described in the literature. Examples of procedures fordetermining molecular weights are gel permeation chromatography (alsoknown as size-exclusion chromatography) and vapor phase osmometry (VPO).These and other procedures are described in numerous publicationincluding:

[0103] P. J. Flory, “Principles of Polymer Chemistry” Cornell UniversityPress (1953), Chapter VII, pp 266-316, and

[0104] “Macromolecules, an Introduction to Polymer Science”, F. A. Boveyand F. H. Winslow, Editors, Academic Press (1979), pp 296-312.

[0105] W. W. Yau, J. J. Kirkland and D. D. Bly, “Modern Size ExclusionLiquid Chromatography”, John Wiley and Sons, New York, 1979.

[0106] A measurement which is complementary to a polymer's molecularweight is the melt index (ASTM D-1238). Polymers of high melt indexgenerally have low molecular weight, and vice versa. Mooney Viscosity(ASTM Procedure D-1646-87) relates indirectly to polymer molecularweight. All other factors being equal, as molecular weight of thepolymer increases, so too does the Mooney viscosity.

[0107] ASTM Procedures D-1238 and D-1646-87 appear in Volumes 8 and 9,respectively, of the aforementioned Annual Book of ASTM Standards.

[0108] A preferred method, and the method employed to determine themolecular weights of polymers as set forth herein, is gel permeationchromatography (GPC). For polyolefins, polyolefinic standards areusually employed. Molecular weights of acrylate polymers are preferablydetermined employing polyacrylate standards.

[0109] As noted hereinabove, this invention relates to polymericcompositions. In a preferred embodiment, the polymeric compositioncomprises from about 25% to about 75% by weight of (A) an ethylene-alphaolefin copolymer wherein the ethylene content ranges from about 30 mole% to about 85 mole %; and from about 75% to about 25% by weight of (B) apolymethacrylate copolymer comprising units derived from

[0110] (a) about 35 mole % to about 95 mole % of alkyl methacrylateester monomers containing from about 9 to about 25 carbon atoms in theester group and

[0111] (b) about 65 mole % to about 5 mole % of alkyl methacrylate estermonomers containing from about 7 to about 12 carbon atoms in the estergroup, and optionally

[0112] (c) about 0.2 mole % to about 10 mole % of at least one member ofthe group consisting of alkyl methacrylate ester monomers containingfrom 2 to about 8 carbon atoms in the ester group, which esters aredifferent from methacrylate esters (a) and (b), vinyl aromatic monomersand nitrogen-containing vinyl monomers, with the proviso that no morethan 60% by weight of the esters contain not more than 11 carbon atomsin the ester group, wherein the weight ratio of (A): (B) ranges fromabout 25:75 to about 75:25.

[0113] Polymeric compositions of this invention can be prepared bymixing together the ethylene aliphatic olefin (A) and the alkyl acrylatecopolymer (B).

[0114] Other Additives

[0115] As mentioned, lubricating oil compositions of this invention maycontain other components. The use of such additives is optional and thepresence thereof in the compositions of this invention will depend onthe particular use and level of performance required. Thus the otheradditive may be included or excluded.

[0116] The compositions may comprise a metal salt, frequently a zincsalt of a dithiophosphoric acid. One or more metal salts ofdithiophosphoric acids may be present in a minor amount to provideadditional extreme pressure, anti-wear and anti-oxidancy performance.

[0117] Other additives that may optionally be used in the lubricatingoils of this invention include, for example, detergents, dispersants,viscosity improvers, oxidation inhibiting agents, pour point depressingagents, extreme pressure agents, anti-wear agents, color stabilizers,seal swell agents, odor masking agents and anti-foam agents.

[0118] These include, but are not limited to, auxiliary extreme pressureagents and corrosion and oxidation inhibiting agents exemplified bychlorinated aliphatic hydrocarbons, organic sulfides and polysulfides,phosphorus esters including dihydrocarbon hydrogen phosphites andtrihydrocarbon phosphites, molybdenum compounds, and the like.

[0119] Auxiliary viscosity improvers (also sometimes referred to asviscosity index improvers or viscosity modifiers) may be included. Theseare exemplified by polymers, including polyisobutenes, polymethacrylicacid esters, diene polymers, polyalkyl styrenes, esterifiedstyrene-maleic anhydride copolymers, alkenylarene-conjugated dienecopolymers and polyolefins. Multifunctional viscosity improvers, otherthan those of the present invention, which also have dispersant and/orantioxidancy properties are known and may optionally be used in additionto the products of this invention. Such products are described innumerous publications including those mentioned in the Background of theInvention.

[0120] Pour point depressants are a particularly useful type of additiveoften included in the lubricating oils described herein. See forexample, page 8 of “Lubricant Additives” by C. V. Smalheer and R.Kennedy Smith (Lezius-Hiles Company Publisher, Cleveland, Ohio, 1967).Pour point depressants useful for the purpose of this invention,techniques for their preparation and their use are described in U.S.Pat. Nos. 2,387,501; 2,015,748; 2,655,479; 1,815,022; 2,191,498;2,666,748; 2,721,877; 2,721,878; and 3,250,715 which are expresslyincorporated by reference for their relevant disclosures.

[0121] Anti-foam agents used to reduce or prevent the formation ofstable foam include silicones or organic polymers. Examples of these andadditional anti-foam compositions are described in “Foam ControlAgents”, by Henry T. Kerner (Noyes Data Corporation, 1976), pages125-162.

[0122] Detergents and dispersants may be of the ash-producing or ashlesstype. The ash-producing detergents are exemplified by oil solubleneutral and basic salts of alkali or alkaline earth metals with sulfonicacids, carboxylic acids, phenols or organic phosphorus acidscharacterized by a least one direct carbon-to-phosphorus linkage.

[0123] The term “basic salt” is used to designate metal salts whereinthe metal is present in stoichiometrically larger amounts than theorganic acid radical. Basic salts and techniques for preparing and usingthem are well known to those skilled in the art and need not bediscussed in detail here.

[0124] Ashless detergents and dispersants are so-called despite the factthat, depending on its constitution, the detergent or dispersant mayupon combustion yield a nonvolatile residue such as boric oxide orphosphorus pentoxide; however, it does not ordinarily contain metal andtherefore does not yield a metal-containing ash on combustion. Manytypes are known in the art, and any of them are suitable for use in thelubricants of this invention. The following are illustrative:

[0125] (1) Reaction products of carboxylic acids (or functionalderivatives thereof) containing at least about 34 and preferably atleast about 54 carbon atoms with nitrogen containing compounds such asamine, organic hydroxy compounds such as phenols and alcohols, and/orbasic inorganic materials.

[0126] (2) Reaction products of relatively high molecular weightaliphatic or alicyclic halides with amines, preferably polyalkylenepolyamines. These may be characterized as “amine dispersants”.

[0127] (3) Reaction products of alkyl phenols in which the alkyl groupscontains at least about 30 carbon atoms with aldehydes (especiallyformaldehyde) and amines (especially polyalkylene polyamines), which maybe characterized as “Mannich dispersants”.

[0128] (4) Products obtained by post-treating the carboxylic amine orMannich dispersants with such reagents as urea, thiourea, carbondisulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substitutedsuccinic anhydrides, nitriles, epoxides, boron compounds, phosphoruscompounds or the like.

[0129] (5) Polymers and copolymers of oil-solubilizing monomers such asdecyl methacrylate, vinyl decyl ether and high molecular weight olefinswith monomers containing polar substituents, e.g., aminoalkyl acrylatesor methacrylates, acrylamides and poly-(oxyethylene)-substitutedacrylates. These may be characterized as “polymeric dispersants”.

[0130] The above-mentioned dispersants and viscosity improvers may beused in addition to the additives of this invention.

[0131] These compositions are well known to those skilled in the art andare described in numerous U.S. patents including. U.S. Pat. No.4,234,435, U.S. Pat. No. 4,904,401, U.S. Pat. No. 4,938,881, U.S. Pat.No. 4,952,328, U.S. Pat. No. 4,957,649, U.S. Pat. No. 4,981,602, U.S.Pat. No. 5,696,060 and 5,696,067, each of which is hereby incorporatedherein by reference for relevant disclosures of additives used inlubricating oils compositions.

[0132] The above-illustrated additives may each be present inlubricating compositions at a concentration of as little as 0.001% byweight, usually ranging from about 0.01% to about 20% by weight. In mostinstances, they each contribute from about 0.1% to about 10% by weight,more often up to about 5% by weight.

[0133] The Oil of Lubricating Viscosity

[0134] The lubricating compositions and methods of this invention employan oil of lubricating viscosity, including natural or syntheticlubricating oils and mixtures thereof. Useful oils of lubricatingviscosity include those having kinematic viscosities ranging from about1 to about 80 centistokes or even higher (cSt) at 100° C. In oneembodiment, the oil of lubricating viscosity is selected to providelubricating compositions with a kinematic viscosity of at least about3.5 cSt, or at least about 4.0 cSt at 100° C.

[0135] Natural oils include animal oils and vegetable oils (e.g. castoroil, lard oil) as well as mineral lubricating oils such as liquidpetroleum derived oils and solvent-treated or acid treated minerallubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types. Oils of lubricating viscosity derived fromcoal or shale are also useful. Synthetic lubricating oils includehydrocarbon oils and halosubstituted hydrocarbon oils such aspolymerized and interpolymerized olefins, etc. and mixtures thereof,alkylated aromatics, for example, alkylbenzenes, polyphenyl, (e.g.,biphenyls, terphenyls, alkylated polyphenyls, etc.), alkylated diphenylethers and alkylated diphenyl sulfides and the derivatives, analogs andhomologues thereof and the like.

[0136] Alkylene oxide polymers and interpolymers and derivatives thereofwhere their terminal hydroxyl groups have been modified byesterification, etherification, etc., constitute another useful class ofknown synthetic lubricating oils.

[0137] Another suitable class of synthetic lubricating oils that can beused comprises the esters of di- and polycarboxylic acids and those madefrom C₅ to C₂₀ monocarboxylic acids and polyols and polyolethers.

[0138] Other synthetic lubricating oils include liquid esters ofphosphorus-containing acids, for example, phosphate esters, polymerictetrahydrofurans and the like, silicon-based oils such as thepolyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils andsilicate oils.

[0139] Unrefined, refined and rerefined oils, either natural orsynthetic (as well as mixtures of two or more of any of these) of thetype disclosed hereinabove can be used in the compositions of thepresent invention. Unrefined oils are those obtained directly fromnatural or synthetic sources without further purification treatment.Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Refined oils include solvent refined oils, hydrorefinedoils, hydrofinished oils, hydrotreated oils, and oils obtained byhydrocracking and hydroisomerization techniques.

[0140] Rerefined oils are obtained by processes similar to those used toobtain refined oils applied to refined oils which have been already usedin service. Such rerefined oils often are additionally processed bytechniques directed to removal of spent additives and oil breakdownproducts.

[0141] Specific examples of the above-described oils of lubricatingviscosity are given in Chamberlin, III, U.S. Pat. No. 4,326,972,European Patent Publication 107,282, and A. Sequeria, Jr., LubricantBase Oil and Wax Processing, Chapter 6, Marcel Decker, Inc., New York(1994), each of which is hereby incorporated by reference for relevantdisclosures contained therein.

[0142] Preferred oils of lubricating viscosity are mineral oilscontaining at least about 55% aliphatic saturates, less than 0.5%sulfur, preferably less than 0.1% sulfur and more often less than 0.1%sulfur and viscosity index greater than 100.

[0143] API Group III oils containing at least 90% saturates, no morethan 0.03% sulfur, often less than 0.01% sulfur and viscosity index atleast 120 are especially preferred for gear oils of this invention.These are described in American Petroleum Institute (API) publication1509, “Engine Oil Licensing and Certification System”, Appendix E-APIBase Oil Interchangeability Guidelines for Passenger Car Motor Oil andDiesel Engine Oils”.

[0144] The level of unsaturation can be determined by iodine numberdeterminations using the procedure set out in ASTM Procedure D-460.

[0145] A basic, brief description of lubricant base oils appears in anarticle by D. V. Brock, “Lubrication Engineering”, Volume 43, pages184-5, March, 1987, which article is expressly incorporated by referencefor relevant disclosures contained therein.

[0146] The various additives described herein can be added directly tothe lubricant. Preferably, however, they are diluted with asubstantially inert, normally liquid organic diluent such as mineraloil, naphtha, benzene, toluene or xylene, to form an additiveconcentrate. Preferred additive concentrates contain the diluentsreferred to hereinabove. These concentrates usually comprise about 0.1to about 80% by weight of the compositions of this invention and maycontain, in addition, one or more other additives known in the art ordescribed hereinabove. Concentrations such as 15%, 20%, 30% or 50% orhigher may be employed.

[0147] Lubricating Oil Compositions

[0148] The present invention is also directed to lubricating oilcompositions comprising an oil of lubricating viscosity and a total offrom about 1% to about 50% by weight of copolymers (A) and (B) asdescribed hereinabove.

[0149] In one particular embodiment, the lubricating oil composition isan automatic transmission fluid. Automatic transmission fluids of thisinvention typically comprise a major amount of an oil of lubricatingviscosity, a total of from about 3% to about 12%, often to about 10% byweight of a polymeric composition comprising

[0150] (A) from about 1% to about 99% by weight of at least oneethylene-aliphatic olefin copolymer wherein the aliphatic olefinscontain from 3 to about 24 carbon atoms, said copolymer (A) havingnumber average molecular weight ranging from about 600 to about 5000,and

[0151] (B) from about 99% to about 1% by weight of at least onecopolymer comprising units derived from alkyl acrylate ester monomerscontaining from 2 to about 25 carbon atoms in the ester group, andoptionally, from about 0.1% to about 20% by weight of at least onemember of the group consisting of vinyl aromatic monomers andnitrogen-containing vinyl monomers. said copolymer (B) having numberaverage molecular weight ranging from about 10,000 to about 350,000.

[0152] and minor amounts of at least one metal dithiophosphate, sealswell agent, pour point depressant, ashless dispersant and corrosioninhibitor.

[0153] In another embodiment, the lubricating oil composition is a gearoil composition comprising a major amount of an oil of lubricatingviscosity, preferably a Group III oil, a total of from about 3% to about30% by weight of a polymeric composition comprising

[0154] (A) from about 1% to about 99% by weight of at least oneethylene-aliphatic olefin copolymer wherein the aliphatic olefinscontain from 3 to about 24 carbon atoms, said copolymer (A) havingnumber average molecular weight ranging from about 600 to about 5000,and

[0155] (B) from about 99% to about 1% by weight of at least onecopolymer comprising units derived from alkyl acrylate ester monomerscontaining from 2 to about 25 carbon atoms in the ester group, andoptionally, from about 0.1% to about 20% by weight of at least onemember of the group consisting of vinyl aromatic monomers andnitrogen-containing vinyl monomers. said copolymer (B) having numberaverage molecular weight ranging from about 10,000 to about 350,000, andminor amounts of extreme pressure additives, antiwear agents andcorrosion inhibitors.

[0156] The lubricating compositions of this invention are illustrated bythe examples in the following Tables. The lubricating compositions areprepared by combining the specified ingredients, individually or fromconcentrates, in the indicated amounts and oil of lubricating viscosityto make the total 100 parts by weight. The amounts shown are parts byweight and, unless indicated otherwise, are amounts of chemical presenton an oil-free basis. Thus, for example, an additive comprising 50% oilused at 10% by weight in a blend, provides 5% by weight of chemical.These examples are presented for illustrative purposes only, and are notintended to limit the scope of this invention.

EXAMPLE A

[0157] An ATF is prepared by mixing together 3 parts of the product ofExample 2, 0.2 parts of a 65% in mineral oil solution of apolymethacrylate pour point depressant, 250 parts per million parts oflubricating oil composition (ppm) of red dye, 4.5 parts of anethylene-propylene copolymer having {overscore (M)}_(n)˜3300 and{overscore (M)}_(w)/{overscore (M)}_(n)=2.3 (LUCANT HC-2000), 250 ppmsilicone antifoam agent, 7.35 parts of an additive concentratecontaining 40.8 parts of a mixture of dispersants consisting ofpolyisobutylene ({overscore (M)}_(n)˜950) substituted succinicanhydride-polyethylene polyamine reaction product, boratedpolyisobutylene ({overscore (M)}_(n)˜950) substituted succinicanhydride-polyethylene polyamine reaction product, and polyisobutylene({overscore (M)}_(n)˜950) substituted succinic anhydride-pentaerythritolester-polyethylene polyamine reaction product further reacted with2,5-dimercapto-1,3,4-thiadiazole (DMTD), 1.4 parts 85% aqueousphosphoric acid, 2.7 parts dibutyl hydrogen phosphite, 8.2 parts dialkyldiphenylamine, 6.8 parts dodecyl mercaptan-propylene oxide reactionproduct, 0.4 parts 2,5-di(t-nonyldithio)-1,3,4-thiadiazole, 1.4 partsfatty imidazoline, 2.7 parts di-fatty hydrocarbon hydrogen phosphite,1.4 parts borated C₁₆ epoxide, 3% borated magnesium sulfonate, andsufficient mineral oil to make 100 parts concentrate, and sufficientTexaco ATF basestock to prepare 100 parts of ATF.

EXAMPLE B

[0158] An ATF is prepared as in Example A except 4.23 parts LUCANTHC-2000 and 2.82 parts of the product of Example 2.

COMPARATIVE EXAMPLE A

[0159] An ATF is prepared as in Example A except 12.6 parts of theproduct of Example 2 and 0 parts of LUCANT HC-2000.

COMPARATIVE EXAMPLE B

[0160] An ATF is prepared as in Example A except 0 parts of the productof Example 2 and 6 parts of LUCANT HC-2000.

[0161] Viscosity characteristics and shear stability of the ATF areillustrated in the following Table. Viscosity determinations are madeemploying the test procedures indicated.

[0162] Several tests are available to measure a compositions resistanceto shear under conditions of high shear stress. One useful test is theKRL Tapered Bearing Shear Test. This is a published standard testentitled “Viscosity Shear Stability of Transmission Lubricants” and isdescribed in CEC L-45-T93, available from CEC, 61 New Cavendish Street,London WIM 8AR, England. The same test is also published as DIN 51 350,part 6, and is available from Deutsches Institut für Normung,Burgerfenshase 6, 1000 Berlin 30, Germany. Both of these references areincorporated herein by reference. Employing this procedure for 20 hours,the shear loss of several of the foregoing examples is determined.Example: Comp B Comp A A B Tests: −40° C. Brookfield 16,000 7,690 10,4009,230 Viscosity (ASTM D2983) (centipoise) KRL Shear 100° C. vis 6.9477.288 6.922 6.737 (initial) (centistokes) 100° C. vis 6.681 6.35 6.4676.348 (final) (centistokes) Δ viscosity (%) −3.8 −12.9 −6.6 −5.8

[0163] As be seen from the foregoing data, the combination of copolymersprovides shear stability and good viscosity improving characteristicswithout adversely affecting low temperature performance. Moreover, thisis accomplished with reduced total levels of copolymer.

EXAMPLES C-G

[0164] API 75W-90 gear lubricants contain 4.8 parts sulfurizedisobutylene, 1.65 parts of a the product obtained by reacting thehydroxypropyl ester of di-(methylamyl) dithiophosphate with P₂O₅ andneutralizing with a branched primary amine, 1.24 parts of boratedpolyisobutylene ({overscore (M)}_(n)˜950) substituted succinicanhydride-polyethylene polyamine reaction product, 0.25 part alkylatednaphthalene, 5 parts C₁₆₋₁₈ alkylated benzene, 0.35 parts oleyl amine,20 ppm siloxane based antifoam agent, 0.1 part carboxylic polymerantifoam agent, 0.18 part of 2,5-di(t-nonyldithio)-1,3,4-thiadiazole theindicated amounts of LUCANT HC-2000 and product of Example 1 in asufficient amount of the indicated base oil to prepare 100 parts oflubricant. Example C D E F G Base Oil 4 cSt HVI 4 cSt HVI Mineral Oil 4cSt Mineral Oil 4 cSt 4 cSt (API Gp. III) PAO (API Gp. III) PAO PAOLUCANT 12 12 15 15 18 HC2000 Prod Ex. 1 12 12 15 15 18 Kinetic viscosity16.53 14.73 21.42 19.86 26.39 (100° C.) cSt. Kinetic Viscosity 101.6184.14 136.18 120.97 171.50 (40° C.) cSt.

EXAMPLES H-K

[0165] API 75W-90 gear lubricants contain 4.8 parts sulfurizedisobutylene, 1.65 parts of a the product obtained by reacting thehydroxypropyl ester of di-(methylamyl) dithiophosphate with P₂O₅ andneutralizing with a branched alkyl primary amine, 0.15 part oleylimidazoline, 1.5 parts of branched alkyl amine salt of C₁₄₋₁₈ alkylphosphoric acid, 1.74 parts of borated polyisobutylene ({overscore(M)}_(n)˜950) substituted succinic anhydride-polyethylene polyaminereaction product, 0.25 part alkylated naphthalene, 5 parts C₁₆₋₁₈alkylated benzene, 0.35 parts oleyl amine, 0.035 partsmonoisopropanolamine, 0.13 parts oleylamide, 20 ppm siloxane basedantifoam agent, 0.1 part carboxylic polymer antifoam agent, 0.18 part of2,5-di(t-nonyidithio)-1,3,4-thiadiazole, the indicated amounts of LUCANTHC-2000 and product of Example 1 in a sufficient amount of the indicatedbase oil to prepare 100 parts of lubricant. Example H I J K Base Oil 4cSt HVI 4 cSt HVI Mineral Oil 4 cST Mineral Oil 4 cSt (API Gp. III) PAO(API Gp. III) PAO LUCANT HC2000 12 12 15 15 Prod Ex. 1 12 12 15 15Kinetic viscosity 15.96 14.63 21.21 19.51 (100° C.) cSt. KineticViscosity 96.39 84.18 136.89 120.19 (40° C.) cSt.

EXAMPLES L-O

[0166] API 75W-90 gear lubricants contain 4.8 parts sulfurizedisobutylene, 1.9 parts of C₁₄₋₁₆ phosphite, 0.59 parts of a the productobtained by reacting the hydroxypropyl ester of di-(methylamyl)dithiophosphate with P₂O₅ and neutralizing with a branched alkyl primaryamine, 0.15 part oleyl imidazoline, 1.5 parts of branched alkyl aminesalt of C₁₄₋₁₈ alkyl phosphoric acid, 1.74 parts of boratedpolyisobutylene ({overscore (M)}_(n)˜950) substituted succinicanhydride-polyethylene polyamine reaction product, 0.25 part alkylatednaphthalene, 5 parts C₁₆₋₁₈ alkylated benzene, 0.4 parts oleyl amine, 20ppm siloxane based antifoam agent, 0.1 part carboxylic polymer antifoamagent, 0.18 part of 2,5-di(t-nonyldithio)-1,3,4-thiadiazole, theindicated amounts of LUCANT HC-2000 and product of Example 1 in asufficient amount of the indicated base oil to prepare 100 parts oflubricant. Example L M N O Base Oil 4 cSt HVI 4 cSt HVI Mineral Oil 4cDT Mineral Oil 4 cST (API Gp. III) PAO (API Gp. III) PAO LUCANT HC200012 12 15 15 Prod Ex. 1 12 12 15 15 Kinetic viscosity 15.86 14.48 20.8419.23 (100° C.) cSt. Kinetic Viscosity 94.70 82.12 132.12 115.61 (40°C.) cSt.

EXAMPLE P

[0167] A partial synthetic gear oil composition (75W-90) contains 30parts API Group III basestock (Chevron UCBO, 4 cSt (100N)), 29 partsPetro-Canada VHVI 8 cSt (250) basestock, 10 parts isooctyl adipate(Mobil VSA Ester DB-32) 15.5 parts LUCANT HC-2000, 15.5 parts of theproduct of Example 1, 4.8 parts sulfurized isobutylene, 1.76 parts of athe product obtained by reacting the hydroxypropyl ester ofdi-(methylamyl) dithiophosphate with P₂O₅ and neutralizing with abranched alkyl primary amine, 1.51 parts of borated polyisobutylene (M950) substituted succinic anhydride-polyethylene polyamine reactionproduct, 1 part oleyl imidazoline, 50 ppm siloxane based antifoam agent,0.08 part carboxylic polymer antifoam agent, 0.18 part of2,5-di(t-nonyldithio)-1,3,4-thiadiazole, 0.995 parts 4 cStpolyalphaolefin and sufficient mineral oil to bring the total to 100parts by weight. Kinematic viscosity @ 100° C.=27.90.

EXAMPLE 0

[0168] A synthetic gear oil composition (75W-90) contains 70 parts 4 cStpolyalphaolefin basestock, 15 parts LUCANT HC-2000, 15 parts of theproduct of Example 1, 5 parts C₁₆₋₁₈ alkylated benzene, 0.25 partalkylated naphthalene, and 10 parts of an additive concentratecontaining 1.54 parts of an 80% by weight in mineral oil spiritssolution of heptyl-hydroxyphenylthio-substituted 1,3,4-thiadiazole,16.62 parts of a the product obtained by reacting the hydroxypropylester of di-(methylamyl) dithiophosphate with P₂O₅ and neutralizing witha branched alkyl primary amine, 12.5 parts of a 67% in mineral oilsolution of borated polyisobutylene ({overscore (M)}_(n)˜950)substituted succinic anhydride-polyethylene polyamine reaction product,50 parts sulfurized isobutylene, 0.5 part carboxylic polymer antifoamagent, 1.25 part oleylamide, 17.21 parts mineral oil and 0.38 partmonoisopropanolamine.

[0169] Reference Oil 1

[0170] A mineral oil based 80W-90 gear lubricant contains 3.2 partssulfurized isobutylene, 1.16 parts of the product obtained by reactingthe hydroxypropyl ester of di-(methylamyl) dithiophosphate with P₂O₅ andneutralizing with a branched alkyl primary amine, 0.4 part of branchedalkyl amine salt of C₁₄₋₁₈ alkyl phosphoric acid, 0.88 parts of boratedpolyisobutylene ({overscore (M)}_(n)˜950) substituted succinicanhydride-polyethylene polyamine reaction product, 0.6 part sulfurizedfatty olefin/ester/acid mixture, 0.027 parts monoisopropanolamine, 0.1part oleylamide, 0.053 part carboxylic polymer antifoam agent, 0.016part of 2,5-di(t-nonyldithio)-1,3,4-thiadiazole and 0.092 part of alkylhydroxyphenylthio DMTD in a sufficient amount of base oil to prepare 100parts of lubricant. Kinematic viscosity (cSt) @ 40° C.=138.35, @100°=14.66.

[0171] Reference Oil 2

[0172] A synthetic based 75W-90 gear oil composition contains 1.57 partsmixed di-C₁₋₆ alkyl/C₁₋₈ alkenyl hydrogen phosphonate, 25 partspolyisobutylene ({overscore (M)}_(n)˜1000), 0.2 part of aminopropylamine neutralized styrene-C₁₃₋₁₆ maleate copolymer, 0.15 part of2,5-di(t-nonyldithio-1,3,4-thiadiazole), 4.57 parts sulfurizedisobutylene, 1.66 parts of the product obtained by reacting thehydroxypropyl ester of di-(methylamyl) dithiophosphate with P₂O₅ andneutralizing with a branched alkyl primary amine, 0.84 part of theproduct obtained by reacting the hydroxypropyl ester of di-(methylamyl)dithiophosphate with P₂O₅ and neutralizing with a branched alkyl primaryamine, 0.13 part oleylamide, 0.04 part monoisopropanol amine and 0.1part carboxylic polymer antifoam agent, in a 4 cSt. polyolefin oligomerbase oil. Kinematic viscosity (cSt) @ 40° C.=97.40, @ 100°=14.42.

[0173] Reference Oil 3

[0174] A synthetic gear oil composition (75W-90) contains 55.5 parts 4cSt polyalphaolefin basestock, 30.7 parts polyisobutylene having numberaverage molecular weight of about 1500, 5 parts C₁₆₋₁₈ alkylatedbenzene, 0.25 part alkylated naphthalene and 10 parts of the additiveconcentrate used in Example Q.

[0175] Traction is a property used to predict the operating temperatureproperties of fluids. Using the Mini-Traction Machine (MTM) test rigdescribed hereinabove, the traction profiles of lubricant Example Q andReference Oils 1-3 were compared at 75° F. over a range of sliding torolling contacts. Lubricant example Q is identical to Reference oil 3except lubricant Example Q employs the mixture of polymers of theinstant invention while Reference Oil 3 employs a polyisobutylene. Itwas determined that lubricant Example Q runs with the lowest tractioncoefficients throughout the entire slide-roll range, suggesting loweroperating temperatures under various modes of contact. Reference Oil 1had the greatest traction coefficient over the entire range whileReference Oil 2 had somewhat lower traction coefficients compared to Oil3 but substantially greater than the traction coefficients of lubricantExample Q.

[0176] Using the axle durability test rig discussed hereinabove, thetest that compares operating temperatures under five different operatingconditions, the operating temperatures of several lubricating oilcompositions are compared. Specifically, the performance of lubricantexample D and that of lubricant Reference 2 are compared to a baseline80W-90 lubricant, Reference lubricant 1. The test results are presentedas differences in operating temperature of the test oils compared to thebaseline. TABLE I Staged Durability: Operating Temperature Comparison(ΔT(° F.)) Lubricant Stage I Stage II Stage III Stage IV Stage 5 ExampleD −20.8 −30.2 −26 −28.2 −24.8 Reference 2 7.4 −12 4.9 −1.3 −15.3

[0177] From these data, it is apparent that durability of lubricant D isconsistently superior to both the baseline lubricant and the comparativelubricant.

[0178] It is known that some of the materials described above mayinteract in the final formulation, so that the components of the finalformulation may be different from those that are initially added. Forinstance, metal ions (of, e.g., a detergent) can migrate to other acidicsites of other molecules. The products formed thereby, including theproducts formed upon employing the composition of the present inventionin its intended use, may not susceptible of easy description.Nevertheless, all such modifications and reaction products are includedwithin the scope of the present invention; the present inventionencompasses the composition prepared by admixing the componentsdescribed above.

[0179] Each of the documents referred to above is incorporated herein byreference. Except in the examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about”. Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.As used herein, the expression “consisting essentially of” permits theinclusion of substances which do not materially affect the basic andnovel characteristics of the composition under consideration.

[0180] While the invention has been explained in relation to itspreferred embodiments, it is to be understood that various modificationsthereof will become apparent to those skilled in the art upon readingthe specification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications that fallwithin the scope of the appended claims.

What is claimed is:
 1. A lubricating oil composition comprising an oilof lubricating viscosity and a total of from about 1 to about 50% byweight of copolymers comprising (A) at least one ethylene-aliphaticolefin copolymer wherein the aliphatic olefins contain from 3 to about24 carbon atoms, said copolymer (A) having {overscore (M)}_(n) rangingfrom about 600 to about 5000; and (B) at least one copolymer comprisingunits derived from alkyl acrylate ester monomers containing from 2 toabout 25 carbon atoms in the ester group, and optionally, from about0.1% to about 20% by weight of units derived at least one member of thegroup consisting of vinyl aromatic monomers and nitrogen-containingvinyl monomers, said copolymer (B) having {overscore (M)}_(n) rangingfrom about 10,000 to about 350,000; wherein the weight ratio of (A):(B)ranges from about 99:1 to about 1:99.
 2. The lubricating oil compositionof claim 1 wherein copolymer (A) comprises an ethylene-alpha olefincopolymer wherein the ethylene content ranges from about 30 mole % toabout 85 mole %.
 3. The lubricating oil composition of claim 2 whereinthe ethylene content ranges from about 45 to about 55 mole %.
 4. Thelubricating oil composition of claim 2 wherein (A) is anethylene-propylene copolymer wherein the ethylene content ranges fromabout 40 mole % to about 85 mole %.
 5. The lubricating oil compositionof claim 4 wherein. the ethylene content ranges from about 45 to about55 mole %.
 6. The lubricating composition of claim 1 wherein copolymer(B) comprises units derived from monomers comprising from about 5% toabout 75% by weight of alkyl acrylate ester monomers containing from 2to 12 carbon atoms in the ester group and from about 25% to about 95% byweight of alkyl acrylate ester monomers containing from 13 to about 25carbon atoms in the ester group.
 7. The lubricating oil composition ofclaim 1 wherein copolymer (B) comprises units derived from (a) about 35mole % to about 95 mole % of alkyl methacrylate ester monomerscontaining from about 9 to about 25 carbon atoms in the ester group and(b) about 65 mole % to about 5 mole % of alkyl methacrylate estermonomers containing from about 7 to about 12 carbon atoms in the estergroup, and optionally (c) from about 0.1 mole % to about 20 mole % of atleast one member of the group consisting of alkyl methacrylate estermonomers containing from 2 to about 8 carbon atoms in the ester group,which esters are different from methacrylate esters (a) and (b), vinylaromatic monomers and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group.
 8. The lubricating oilcomposition of claim 7 wherein the alkyl moieties of the ester groups ofalkyl methacrylate ester monomer (b) have 2-(C₁₋₄ alkyl) substituents.9. The lubricating oil composition of claim 1 wherein copolymer (B)comprises units derived from (a) about 35 mole % to about 95 mole % ofalkyl methacrylate ester monomers containing from about 13 to about 25carbon atoms in the ester group and (b) about 65 mole % to about 5 mole% of alkyl methacrylate ester monomers containing from about 7 to about12 carbon atoms in the ester group.
 10. The composition of claim 9wherein copolymer (B) further comprises from about 0.1 mole % to about20 mole % of units derived from (c) at least one member of the groupconsisting of alkyl methacrylate ester monomers containing from 2 toabout 8 carbon atoms in the ester group, which esters are different frommethacrylate esters (a) and (b), vinyl aromatic monomers andnitrogen-containing vinyl monomers, with the proviso that no more than60% by weight of the esters contain not more than 11 carbon atoms in theester group.
 11. The lubricating oil composition of claim 9 wherein thealkyl moieties of the ester groups of alkyl methacrylate ester monomer(b) have 2-(C₁₋₄ alkyl) substituents.
 12. The lubricating oilcomposition of claim 11 wherein monomer (b) comprises 2-ethylhexylmethacrylate.
 13. The lubricating oil composition of claim 1 wherein (A)is an ethylene-alpha olefin copolymer wherein the ethylene contentranges from about 30 mole % to about 85 mole %; and (B) is apolymethacrylate copolymer comprising units derived from (a) about 35mole % to about 95 mole % of alkyl methacrylate ester monomerscontaining from about 9 to about 25 carbon atoms in the ester group and(b) about 65 mole % to about 5 mole % of alkyl methacrylate estermonomers containing from about 7 to about 12 carbon atoms in the estergroup, and optionally (c) about 0.2 mole % to about 10 mole % of atleast one member of the group consisting of alkyl methacrylate estermonomers containing from 2 to about 8 carbon atoms in the ester group,which esters are different from methacrylate esters (a) and (b), vinylaromatic monomers and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group, wherein the weight ratio(A):(B) ranges from about 25:75 to about 75:25.
 14. The lubricating oilcomposition of claim 13 wherein the alkyl moieties of the ester groupsof alkyl methacrylate monomer (b) have 2-(C₁₋₄ alkyl) substituents. 15.The lubricating oil composition of claim 1 wherein (B) further comprisesunits derived from about 0.1% to about 10% by weight of at least onenitrogen containing vinyl monomer.
 16. The lubricating oil compositionof claim 1 wherein (B) is a copolymer prepared by a process comprisingreacting, in the presence of a free radical initiator (1) from about 55%to about 99.9% by weight of one or more alkyl acrylate ester monomerscontaining from 2 to about 25 carbon atoms in the ester group, whereinat least about 50 mole % of the esters contain at least 6 carbon atomsin the ester group, and (2) from about 0.1% to about 45% by weight of atleast one monomer selected from the group consisting of acrylic acidesters containing from 2 to about 8 carbon atoms in the ester group andwhich are different from alkyl acrylate ester monomers (1), vinylaromatic monomers and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group, and optionally, in the presenceof a chain transfer agent, wherein monomer (1), the free radicalinitiator, and if used, the chain transfer agent, are first combined toform a mixture, whereupon from about 10% to about 80% of said mixture ismixed with monomer (2) to form a second mixture; from about 20% to about100% of the mixture of monomers (1) and (2) is heated until an exothermis noted, then while maintaining reaction temperature, first adding thebalance, if any, of the mixture of monomers (1) and (2) over about 0.25hour to about 5 hours followed by addition over 0.25 to about 5 hours ofthe remaining mixture of monomer (1) and initiator, optionally addingadditional initiator, whereupon the reaction is continued to completion.17. The lubricating oil composition of claim 16 wherein monomer (2)comprises a nitrogen containing vinyl monomer.
 18. The lubricating oilcomposition of claim 17 wherein the nitrogen containing vinyl monomer isselected from the group consisting of vinyl substituted nitrogenheterocyclic monomers, dialkylaminoalkyl acrylate monomers,dialkylaminoalkyl acrylamide monomers, N-tertiary alkyl acrylamides, andvinyl substituted amines.
 19. The lubricating oil composition of claim10 wherein (B) is prepared by a process comprising reacting, in thepresence of a free radical initiator (a) the methacrylic acid esterscontaining from about 13 to about 25 carbon atoms in the ester group,and (b) the methacrylic acid esters containing from 7 to about 12 carbonatoms in the ester group, and (c) the at least one monomer selected fromthe group consisting of methacrylic acid esters containing from 2 toabout 8 carbon atoms in the ester group and which are different frommethacrylic acid esters (a) and (b), vinyl aromatic monomers andnitrogen-containing vinyl monomers, with the proviso that no more than60% by weight of the esters contain not more than 11 carbon atoms in theester group, optionally in the presence of a chain transfer agent,wherein monomers (a) and (b), the free radical initiator, and if used,the chain transfer agent, are combined to prepare a first mixture; fromabout 10% to about 80% by weight of the first mixture of monomers (a)and (b) is combined with monomer (c) to prepare a second mixture; fromabout 20% to about 100% of the second mixture is heated until anexotherm is noted; then while maintaining reaction temperature, firstadding the balance, if any, of the second mixture over about 0.25 hourto about 5 hours followed by addition over 0.25 to about 5 hours of theremaining first mixture, optionally adding additional initiator,whereupon the reaction is continued to completion.
 20. The lubricatingoil composition of claim 19 wherein the alkyl moieties of the estergroups of alkyl methacrylate monomer (b) have 2-(C₁₋₄ alkyl)substituents.
 21. The lubricating oil composition of claim 19 wherein(c) comprises at least one nitrogen containing vinyl monomer.
 22. Thelubricating oil composition of claim 1 wherein the oil of lubricatingviscosity comprises at least one mineral oil.
 23. The lubricatingcomposition of claim 1 wherein the oil of lubricating viscositycomprises at least one member selected from the group consisting ofmineral oil and synthetic oil having kinematic viscosity at 100° C.ranging from about 4 to about 10 centistokes.
 24. The lubricating oilcomposition of claim 22 wherein the mineral oil is a Group III oil. 25.The lubricating oil composition of claim 1 further comprising at leastone member of the group consisting of pour point depressants, corrosioninhibitors, extreme pressure additives, antiwear additives,antioxidants, detergents, ashless dispersants, friction modifiers, andantifoam agents.
 26. An automatic transmission fluid comprising a majoramount of an oil of lubricating viscosity, a total of from about 3% toabout 10% by weight of a polymeric composition comprising (A) from about1% to about 99% by weight of at least one ethylene-aliphatic olefincopolymer wherein the aliphatic olefins contain from 3 to about 24carbon atoms, said copolymer (A) having number average molecular weightranging from about 600 to about 5000, and (B) from about 99% to about 1%by weight of at least one copolymer comprising units derived from alkylacrylate ester monomers containing from 2 to about 25 carbon atoms inthe ester group, and optionally, from about 0.1% to about 20% by weightof at least one member of the group consisting of vinyl aromaticmonomers and nitrogen-containing vinyl monomers. said copolymer (B)having number average molecular weight ranging from about 10,000 toabout 350,000. and minor amounts of at least one metal dithiophosphate,seal swell agent, pour point depressant, ashless dispersant andcorrosion inhibitor.
 27. A gear oil composition comprising a majoramount of a Group III oil, a total of from about 3% to about 30% byweight of a polymeric composition comprising (A) from about 1% to about99% by weight of at least one ethylene-aliphatic olefin copolymerwherein the aliphatic olefins contain from 3 to about 24 carbon atoms,said copolymer (A) having number average molecular weight ranging fromabout 600 to about 5000, and (B) from about 99% to about 1% by weight ofat least one copolymer comprising units derived from alkyl acrylateester monomers containing from 2 to about 25 carbon atoms in the estergroup, and optionally, from about 0.1% to about 20% by weight of atleast one member of the group consisting of vinyl aromatic monomers andnitrogen-containing vinyl monomers. said copolymer (B) having numberaverage molecular weight ranging from about 10,000 to about 350,000, andminor amounts of extreme pressure additives, antiwear agents andcorrosion inhibitors.
 28. A polymeric composition comprising a mixtureof (A) from about 1% to about 99% by weight of at least oneethylene-aliphatic olefin copolymer wherein the aliphatic olefinscontain from 3 to about 24 carbon atoms, said copolymer (A) havingnumber average molecular weight ranging from about 600 to about 5000,and (B) from about 99% to about 1% by weight of at least one copolymercomprising units derived from alkyl acrylate ester monomers containingfrom 2 to about 25 carbon atoms in the ester group, and optionally, fromabout 0.1% to about 20% by weight of at least one member of the groupconsisting of vinyl aromatic monomers and nitrogen-containing vinylmonomers. said copolymer (B) having number average molecular weightranging from about 10,000 to about 350,000.
 29. The polymericcomposition of claim 28 wherein copolymer (A) comprises anethylene-alpha olefin copolymer wherein the ethylene content ranges fromabout 30 mole % to about 85 mole %.
 30. The polymeric composition ofclaim 29 wherein (A) is an ethylene-propylene copolymer wherein theethylene content ranges from about 40 mole % to about 85 mole %.
 31. Thepolymeric composition of claim 29 wherein copolymer (B) comprises unitsderived from (a) about 35 mole % to about 95 mole % of alkylmethacrylate ester monomers containing from about 9 to about 25 carbonatoms in the ester group and (b) about 65 mole % to about 5 mole % ofalkyl methacrylate ester monomers containing from about 7 to about 12carbon atoms in the ester group, and optionally (c) from about 0.1 mole% to about 20 mole % of at least one member of the group consisting ofalkyl methacrylate ester monomers containing from 2 to about 8 carbonatoms in the ester group, which esters are different from methacrylateesters (a) and (b), vinyl aromatic monomers and nitrogen-containingvinyl monomers, with the proviso that no more than 60% by weight of theesters contain not more than 11 carbon atoms in the ester group.
 32. Thepolymeric composition of claim 30 wherein the alkyl moieties of theester groups of alkyl methacrylate monomer (b) have 2-(C₁₋₄ alkyl)substituents.
 33. The polymeric composition of claim 28 whereincopolymer (B) comprises units derived from (a) about 35 mole % to about95 mole % of alkyl methacrylate ester monomers containing from about 13to about 25 carbon atoms in the ester group and (b) about 65 mole % toabout 5 mole % of alkyl methacrylate ester monomers containing fromabout 7 to about 12 carbon atoms in the ester group.
 34. The polymericcomposition of claim 33 wherein the alkyl moieties of the ester groupsof alkyl methacrylate monomer (b) have 2-(C₁₋₄ alkyl) substituents. 35.The polymeric composition of claim 30 wherein monomer (b) comprises2-ethylhexyl methacrylate.
 36. The polymeric composition of claim 32comprising from about 25% to about 75% by weight of (A) anethylene-alpha olefin copolymer wherein the ethylene content ranges fromabout 30 mole % to about 85 mole %; and from about 75% to about 25% byweight of (B) a polymethacrylate copolymer comprising units derived from(a) about 35 mole % to about 95 mole % of alkyl methacrylate estermonomers  containing from about 9 to about 25 carbon atoms in the estergroup and (b) about 65 mole % to about 5 mole % of alkyl methacrylateester monomers containing from about 7 to about 12 carbon atoms in theester group, and optionally (c) from about 0.2 mole % to about 10 mole %of at least one member of the group consisting of alkyl methacrylateester monomers containing from 2 to about 8 carbon atoms in the estergroup, which esters are different from methacrylate esters (a) and (b),vinyl aromatic monomers and nitrogen-containing vinyl monomers, with theproviso that no more than 60% by weight of the esters contain not morethan 11 carbon atoms in the ester group.
 37. The lubricating oilcomposition of claim 36 wherein the alkyl moieties of the ester groupsof alkyl methacrylate monomer (b) have 2-(C₁₋₄ alkyl) substituents. 38.The polymeric composition of claim 36 wherein (B) further comprisesunits derived from about 0.1% to about 10% by weight of at least onenitrogen containing monomer.
 39. The polymeric composition of claim 36wherein (B) is a copolymer prepared by a process comprising reacting, inthe presence of a free radical initiator (a) the methacrylic acid esterscontaining from about 9 to about 25 carbon atoms in the ester group, and(b) the methacrylic acid esters containing from 7 to about 12 carbonatoms in the ester group, and (c) the at least one monomer selected fromthe group consisting of methacrylic acid esters containing from 2 toabout 8 carbon atoms in the ester group and which are different frommethacrylic acid esters (a) and (b), vinyl aromatic monomers andnitrogen-containing vinyl monomers, with the proviso that no more than60% by weight of the esters contain not more than 11 carbon atoms in theester group, optionally in the presence of a chain transfer agent,wherein monomers (a) and (b), the free radical initiator, and if used,the chain transfer agent, are combined to prepare a first mixture; fromabout 10% to about 80% by weight of the first mixture of monomers (a)and (b) is combined with monomer (c) to prepare a second mixture; fromabout 20% to about 100% of the second mixture is heated until anexotherm is noted; then while maintaining reaction temperature, firstadding the balance, if any, of the second mixture over about 0.25 hourto about 5 hours followed by addition over 0.25 to about 5 hours of theremaining first mixture, optionally adding additional initiator,whereupon the reaction is continued to completion.
 40. The polymericcomposition of claim 39 wherein the alkyl moieties of the ester groupsof alkyl methacrylate monomer (b) have 2-(C₁₋₄ alkyl) substituents. 41.A polymeric composition prepared by mixing together (A) from about 1% toabout 99% by weight of at least one ethylene-aliphatic olefin copolymerwherein the aliphatic olefins contain from 3 to about 24 carbon atoms,said copolymer having number average molecular weight ranging from about600 to about 5000, and (B) from about 99% to about 1% by weight of atleast one copolymer comprising units derived from alkyl acrylate estermonomers containing from 2 to about 25 carbon atoms in the ester group,and optionally, from about 0.1% to about 20% by weight of at least onenitrogen containing monomer. said copolymer (B) having number averagemolecular weight ranging from about 10,000 to about 350,000.